J O U R N A L O F C H E M I S T R Y Materials Preparation and characterization of metal complexes with an extended TTF dithiolato ligand, bis(propylenedithiotetrathiafulvalenedithiolato)-nickelate and -cuprate† Mieko Kumasaki, Hisashi Tanaka and Akiko Kobayashi* Department of Chemistry, Faculty of Science, T he University of T okyo, Hongo, Bunkyo-ku, T okyo 113, Japan Novel monoanionic nickel and dianionic copper complexes with the extended TTF dithiolato ligand, propylenedithiotetrathiafulvalenedithiolate [ptdt2-=(S8C9H6)2-], have been synthesized. Characterization of monoanionic tetraphenylphosphonium and tetramethylammonium salts of Ni(ptdt)2- and the dianionic tetraphenylphosphonium salt of Cu(ptdt)22- have been performed, using cyclic voltammetry, electrical resistivity measurements, magnetic susceptibility measurements and X-ray crystal structure determination.The geometries around the Ni atoms are almost square planar. In both Ni complexes, one of the extended ligands of Ni(ptdt)2- is overlapping with that of the adjacent anion separated by about half of the unit of the molecule, forming a one-dimensional chain. The adjacent chains are connected by transverse short S,S contacts.Cu(ptdt)22- has a distorted tetrahedral geometry around the Cu atom and the dihedral angle between the planes of the dithiolato ligand is 54.2 °. The crystal structures of Ni(ptdt)2- and Cu(ptdt)22- complexes show the possibility of novel 2D or 3D intermolecular contacts through ptdt ligands. The complex [Me4N][Ni(ptdt)2]·Me2CO is a semiconductor with a room temperature conductivity of 1.4×10-3 S cm-1 and activation energy of 9.9×10-2 eV.In recent investigations of molecular conductors and supercon- metal complexes with elongated p-ligands will provide new types of molecular conducting systems. Here, we report the ductors, there is increasing interest in molecules with extended p-conjugation frameworks.1 This is because such molecules preparation of a new ligand, propylenedithiotetrathiafulvalenedithiolate (C9H6S82-, ptdt2-) and the crystal structures of a can stabilize multi-cation states and increase intermolecular interactions.Furthermore metal complexes with extended p precursor of the ligand ptdt(CH2CH2CN)2, the tetraphenylphosphonium salt of a square-planar Ni complex, (Ph4P)- ligands are expected to open a new field of molecular conductors owing to the variety of central metal atoms and possible [Ni(ptdt)2]·1.4Me2CO 1, the tetramethylammonium salt of the Ni complex, (Me4N)[Ni (ptdt)2]Me2CO 2 and a tetrahedral modifications of the extended p-conjugation ligands.However, only a few conducting metal complexes with elongated dithi- Cu complex, (Ph4P)2[Cu(ptdt)2]·1.2Me2CO 3.olene-type ligands have been prepared. Recently, Narvor et al. have reported the synthesis, structure Experimental and conductive properties of nickel complexes of tetrathiafulva- Synthesis and crystal growth lenedithiolate, which exhibited a fairly high conductivity in the neutral state.2 However bulky terminal SR (R=alkyl) groups Reagent-grade tetrahydrofuran was purified and distilled over sticking out from the molecular plane might prevent close sodium–benzophenone prior to use. Methanol was refluxed intermolecular S,S contacts.Nakano et al. have prepared over Mg and distilled; other solvents and chemicals were used metal complexes of ethylenedithiotetrathiafulvalenedithiolate as received. Schlenk techniques were used in carrying out (C8H4S82-, etdt2-).3 The etdt metal complexes, however, have manipulations under argon atmosphere.NMR spectra were poor solubility as is often the case for molecules with extended measured on a JEOL JNM-EX 270 Model spectrometer. p-conjugation, which is unfavorable for obtaining good single Cyclic voltammetry data were recorded by BAS CV-60W. The crystals. Thus a crystal structure of an M(etdt)2 compound ptdt2- ligand was synthesized as shown in Scheme 1.has not been reported. Therefore, an improvement of the Initially, we used p-acetoxybenzyl as the protecting group solubility seems to be necessary for further development. in cross-coupling to synthesize the unsymmetrical precursor of In order to increase solubility, we prepared a new ligand ptdt2-.Gemmell et al.4 and Misaki et al.5 reported that their which incorporates an additional methylene group into etdt2-. unsymmetrical TTF derivatives were obtained in high yields One of the important requirements for constituent molecules using this protecting group. In our case, however, the crossof the molecular conductors is good planarity of the molecules. coupling method gave more than five products and our target However in metal complexes with tetrathiafulvalenedithiolate, molecule was obtained in only 4.6% yield.We then used the planarity of the whole molecule may be not so important. cyanoethyl as the protecting group, and succeeded in obtaining The long ligand will be preferably favorable for increasing 7 in high yield. overlapping between the molecules. Each of the two tetrathiafulvalene moieties joined to the central transition metal atom Preparation of 4,5-propylenedithio-1,3-dithiole-2-thione 4.will be able to produce S,S networks even if the metal (Et4N)2[Zn(dmit)2] (43 g) was dissolved in 200ml of acetocomplex molecule has a twisted conformation. Thus transition nitrile and 26 g of 1,3-dibromopropane was added and the solution stirred for 2 d at room temperature.The resulting orange precipitate was filtered oV and to the residue dichloro- † Presented at the 58th Okazaki Conference, Recent Development and methane was added and the solution was filtered. Activated Future Prospects of Molecular Based Conductors, Okazaki, Japan, 7–9 March 1997. charcoal (0.2 g) was added to the filtrate and the solution was J. Mater.Chem., 1998, 8(2), 301–307 301S S S S S S Zn S S S S [Et4N]2[Zn(dmit)2] S S S S S 4 Br Br CH3CN [(C2H5)4N]2 [Et4N]2[Zn(dmit)2] NC Br CH3CN S S S S CN CN S 5 S S S S CN CN O 6 Hg(OAc)2–CHCl3 AcOH S S S S CN CN 7 S S S S 4 + 6 P(OEt)3 S S S–NMe4 + S–NMe4 + S S S S NMe4OH MeOH S S S S S S S S S S S S S S S S M S S S S S S S S S S S S S S S S M M2+ (NMe4) x 8 M = Ni 9 M = Cu 1 M = Ni 3 M = Cu cation exchange (PPh4)m(solvent) n Scheme 1 refluxed for 30 min. The solution was filtered and ethanol was to -20 °C.Orange yellow needle crystals were obtained. Yield 3.1 g. (60.5% based on 6) (Found: C, 37.48; H, 2.95; N, 5.84; S, added. Yellow crystals were obtained from this solution at -20 °C. Yield 19.6g. {68.7% based on (Et4N)2[Zn(dmit)2]}. 53.30. C15H14N2S8 requires C, 37.63; H, 2.95; N, 5.85; S, 53.58%). 1H NMR(270 MHz, CDCl3, ref.TMS) dH: 3.08 (4H, t, J= 7.1Hz), 2.76–2.69 (8H, m), 2.41 (2H, m). Preparation of 4,5-bis(2-cyanoethylthio)-1,3-dithiole-2-thione 5. (Et4N)2[Zn(dmit)2] (10 g) was dissolved in 80 ml of acetonitrile and 7 g of 3-bromopropionitrile was added to the Preparation of 8. The following procedures were performed under an argon atmosphere. To 101 mg of 7 in a 300 ml flask solution and was refluxed for 1 h. The solution was filtered oV and then concentrated.After adding 125 ml of dichloro- was added 22 ml of THF and the solution was cooled to -78 °C using a dry-ice bath. The tetramethylammonium salts methane, the solution was washed three times with water. Then the solution was dried with magnesium sulfate.After were obtained by deprotection with 0.2 ml of Me4NOH followed by addition of 20 ml of a methanol solution containing removing the drying agent, ethanol was added at -20 °C. Brown yellow needle crystals were obtained. Yield 5.6 g. 5 mg of NiCl2·6H2O. This solution was stirred overnight and then gradually warmed to room temperature. The obtained {66.1% based on (Et4N)2[Zn(dmit)2]}.precipitate was filtered oV and dried in vacuo (1 mmHg) and obtained as a brown powder. 4,5-Bis(2-cyanoethylthio)-1,3-dithiole-2-one 6. To 4.8 g of 5 and 12.1 g of Hg(CH3COO)2 in a 300 ml flask were added 160 ml of chroloform–acetic acid (351). The solution was Preparation of 9. The following procedures were performed under an argon atmosphere.To 101 mg of 7 in a 300 ml flask stirred at room temperature overnight. A white precipitate was obtained and filtered oV using Celite. The filtered solution was was added 22 ml of THF. The solution was then cooled to -78 °C using a dry-ice bath. The tetramethylammonium salts washed with water, saturated NaHCO3 aqueous solution, water and dried with Na2SO4. After removing the drying was prepared by deprotection with 0.2 ml of Me4NOH followed by addition of a 20 ml methanol solution of 5 mg of agent, the filtrate was concentrated and ethanol was added at -20 °C.Milky white crystals were obtained. Yield 3.7 g. CuCl2·2H2O at -78 °C. This solution was stirred overnight and the reaction mixture was warmed gradually to room (83.7% based on 5). temperature. The obtained green precipitate was filtered oV and dried at 1 mmHg pressure. 2,3-Bis (2-cyanoethylthio)-6,7-propylenedithiotetrathiafulvalene 7.To 4.4 g of 4 and 3.0 g of 6 in a 200 ml flask under an argon atmosphere was added freshly distilled P(OC2H5)3 Preparation of 1 and 2. Compound 8 and tetraphenylphosphonium bromide were placed in separate compartments of (130 ml) under flushing argon.The reaction mixture was then raised to 110 °C. After reaction for 1 h, the red solution was an H-cell under argon. Acetone was poured into the H-cell which was left to stand undisturbed. After 10 days, red plate cooled to room temperature and a precipitate was obtained at -20 °C. The precipitate was dissolved into dichloromethane and crystals of 1 were obtained. Crystals of 2 were obtained unexpectedly in the procedure of the electrocrystallization 7 was isolated by dichloromethane silica gel column chromatography.The solution was concentrated, ethanol added and cooled using a current of 0.1 mA in an H-shaped cell with platinum 302 J. Mater. Chem., 1998, 8(2), 301–307electrodes under an argon atmosphere. The crystals were the non-hydrogen atoms and refinement was by full-matrix least-squares methods.The calculated positions of hydrogen obtained using 10 mg of 8 and tetramethylammonium bromide and then adding 20 ml of acetone. Black block crystals were atoms [d(C–H)=0.95 A ° ] were included in the final calculation except for the solvent molecules. The populations of the solvent collected from the bottom of the H-cell after 3 weeks. molecules are refined initially and fixed in the final calculation.Atomic scattering factors were taken from ref. 6. The absolute Preparation of 3. Compound 9 and tetraphenylphosphonium bromide were placed in separate compartments of an H-cell configuration of the crystal structure of 7 could not be determined owing to an insuYcient number of Friedel pair reflec- under argon.Acetone was poured into the H-cell which was left to stand undisturbed. After 10 days green plate crystals tions. All calculations were performed using the teXsan crystallographic software package of the Molecular Structure were obtained. Corporation.7 Full crystallographic details excluding structure factors have been deposited at the Cambridge Crystallographic Cyclic voltammetry Data Centre (CCDC).See Information for Authors, J. Mater. Cyclic voltammetry (CV) of (Me4N)2[Cu(ptdt)2] 9 and Chem., 1998, Issue I. Any request to the CCDC for this material (Me4N)[Ni (ptdt)2] 8 were carried out in acetonitrile using should quote the full literature citation and the reference (Bu4N)ClO4 as supporting electrolyte at 100 mV s-1 over the number 1145/54.potential range -1.8 to +2.0 V. The working and counter electrode were platinum and the reference electrode was Magnetic susceptibility Ag/Ag+. (Me4N)2[Cu(ptdt)2] and (Me4N)[Ni(ptdt)2] showed qualitatively similar features, but the latter’s peak intensities The magnetic susceptibility was measured at a field of 2 T decreased on repeated scanning due to the formation of an from 300 to 2 K using a Quantum Design MPMS SQUID insoluble film of the neutral 151 salt on the electrode.magnetometer. (Me4N)2[Cu(ptdt)2] showed one reduction process at-0.73 V vs. SCE and two oxidation process at -0.08 and +1.15 V vs. Electrical resistivity SCE, while (Me4N)[Ni (ptdt)2] showed peaks at-0.45,-0.15, Resistivities were measured by a conventional four-probe and +1.20 V.The CV data of these compounds indicate that method using gold wire (0.02 mm) with gold paint as a contact the peak at -0.08 V of the Cu complex appears to correspond in the temperature range 300–77 K. to the process Cu(ptdt)22-�Cu(ptdt)2- and the peak at -0.45 V of the Ni complex corresponds to the process Ni(ptdt)22-�Ni(ptdt)2-; Ni (ptdt)22- is readily oxidized to Results and Discussion Ni(ptdt)2-.Crystal structures Crystal structure determination 2,3-Bis (2-cyanoethylthio)-6,7-propylenedithiotetrathiafulvalene5ptdt( CH2CH2CN)2 7. The ptdt(CH2CH2CN)2 molecule is Intensity data were measured on Rigaku AFC-7R, AFC-5R or AFC-6S automated four-circle diVractometers using graphite shown in Fig. 1(a) and selected bond lengths are listed in Table 2. Atoms S(1), S(2), S(3), S(4), C(1) and C(2) lie in a good plane monochromated Mo-Ka radiation at 23 °C.Empirical absorption corrections were performed. The experimental details and A while atoms S(3), S(4), S(5), S(6), S(7), S(8), C(3), C(4), C(5) and C(6) including a tetrathiafulvalene group form a fairly crystal data are listed in Table 1. The structure were solved by direct methods.Anisotropic temperature factors were used for good plane B. Atoms S(7), S(8), C(5), C(6), C(7), C(8) and Table 1 Crystal and experimental data (Me4N)[Ni(ptdt)2]·Me2CO (Ph4P)[Ni(ptdt)2]·1.4Me2CO (Ph4P)2[Cu(ptdt)2]·1.2Me2CO ptdt(CH2CH2CN)2 formula C25H30S16NNiO C47.40H44.60S16PNiO1.40 C69.60H59.20S16CuP2O1.20 C15H14N2S8 crystal color, habit black, block red, plate green, block orange, needle crystal system triclinic monoclinic monoclinic monoclinic formula mass 932.18 1190.53 1553.29 478.77 a/A ° 12.799(1) 28.567(3) 21.420(6) 9.96(3) b/A° 13.306(1) 8.289(6) 11.826(4) 6.707(9) c/A ° 12.539(2) 25.295(6) 29.18(1) 15.08(5) a/degrees 91.172(9) b/degrees 108.421(7) 108.08(1) 91.20(3) 101.0(2) c/degrees 109.482(6) V/A ° 3 1890.9(4) 5694(3) 7390(3) 988(3) space group P19 C2/c P2/c P21 Z 2 4 4 2 Dx/g cm-3 1.637 1.389 1.396 1.608 dimensions/mm 0.30×0.20×0.20 0.30×0.20×0.20 0.20×0.30×0.10 0.30×0.10×0.60 radiation Mo-Ka Mo-Ka Mo-Ka Mo-Ka diVractometer AFC 5R AFC 7R AFC 5R AFC 6S m/cm-1 14.21 9.93 8.34 9.05 2hmax/degrees 55.0 55.0 55.0 55.3 total reflections 9230 7155 18 277 2619 reflections used 8693 7007 17 814 2483 parameters refined 397 288 790 226 scan technique v–2h v v v–2h scan width 1.57+0.30tanh 0.73+0.30tanh 0.73+0.30tanh 1.10+0.30tanh v scan speed 12 16 16 8.0 (degrees min-1) R, Rw 0.039, 0.034 0.060, 0.058 0.065, 0.055 0.035, 0.036 final shift/error 0.67 0.59 0.06 0.06 residual d/e A° -3 0.34 0.77 0.38 0.24 J.Mater. Chem., 1998, 8(2), 301–307 303Fig. 2 (a) ORTEP drawing of the monoanion Ni(ptdt)2- showing the atom labelling at the 50% probability level.(b) Side view of Ni(ptdt)2- in (Ph4P)[Ni(ptdt)2]·1.4Me2CO. Table 3 Selected bond lengths (A ° ) and angles (degrees) for (Ph4P)[Ni(ptdt)2]·1.4Me2CO Ni(1)MS(1) 2.154(1) S(6)MC(6) 1.752(7) Ni(1)MS(2) 2.167(2) S(7)MC(5) 1.736(7) S(1)MC(1) 1.735(7) S(7)MC(7) 1.809(8) S(2)MC(2) 1.707(6) S(8)MC(6) 1.739(8) S(3)MC(1) 1.765(6) S(8)MC(9) 1.783(8) S(3)MC(3) 1.757(7) C(1)MC(2) 1.345(9) S(4)MC(2) 1.762(7) C(3)MC(4) 1.323(8) S(4)MC(3) 1.773(7) C(5)MC(6) 1.36(1) S(5)MC(4) 1.755(7) C(7)MC(8) 1.49(1) S(5)MC(5) 1.757(7) C(8)MC(9) 1.54(1) S(6)MC(4) 1.765(7) Fig. 1 (a) ORTEP drawing8 of ptdt(CH2CH2CN)2 showing the atom labelling at the 50% probability level. (b) Side view of S(1)MNi(1)MS(1) 180.00 S(1)MNi(1)MS(2) 87.07(7) ptdt(CH2CH2CN)2.S(1)MNi(1)MS(2) 92.93(7) S(1)MNi(1)MS(2) 92.93(7) S(1)MNi(1)MS(2) 87.07(7) S(2)MNi(1)MS(2) 180.00 Table 2 Selected bond lengths (A° ) for ptdt(CH2CH2CN)2 S(1)MC(1) 1.752(6) S(7)MC(5) 1.738(6) and angles of Ni(ptdt)2- are similar to those of the analogous S(2)MC(2) 1.761(6) S(7)MC(7) 1.821(8) compound in which propylene groups are substituted for the S(3)MC(1) 1.751(6) S(8)MC(6) 1.75 two methyl groups [2.172(5), 2.160(7) A ° and 93.3(2), 86.7(2) °, S(3)MC(3) 1.744(6) S(8)MC(9) 1.847(9) respectively].2 The central C(3)MC(4) bond length is S(4)MC(2) 1.753(6) C(1)MC(2) 1.328(8) 1.323(8) A ° , which is shorter than that in 7.The seven-mem- S(4)MC(3) 1.771(6) C(3)MC(4) 1.342(7) bered heteroring is flexible and those in ptdt(CH2CH2CN)2 1 S(5)MC(4) 1.743(6) C(5)MC(6) 1.310(8) S(5)MC(5) 1.752(6) C(7)MC(8) 1.46(1) and Ni(ptdt)2- 2 bend at S(7) and S(8) in the opposite S(6)MC(4) 1.752(6) C(8)MC(9) 1.50(1) direction.The crystal structure of 1 [Fig. 3(a)] showed that S(6)MC(6) 1.766(6) one of the ligands of Ni(ptdt)2- is overlapping with that of the adjacent anion separated by the translation 1/2a-1/2b, forming a one-dimensional chain along [110].The overlapping C(9) form a seven-membered heteroring. This seven-membered mode of Ni(ptdt)2- is shown in Fig. 3(b), which shows that ring adopts a chair conformation and is tilted from plane B. The central C(3)MC(4) bond length is 1.342(7) A ° , which is similar to that of the CNC bond length in neutral bis(propylenedithio)- tetrathiafulvalene [1.341(4) A ° ].9 The C(1)MC(2) and C(5)M C(6) distances are 1.328(8) and 1.310(8) A ° , respectively, which are shorter than the central C(3)MC(4). Fig. 1(b) shows that C(7), C(8) and C(9) show the largest deviation from plane A, of 4.06, 4.27 and 3.91 A ° , respectively. The dihedral angle of planes A and B is 21.25 °. (Ph4P)[Ni(ptdt)2]·1.4Me2CO 1. The Ni(ptdt)2- anion is shown in Fig. 2(a) and selected bond lengths and angles are shown in Table 3.The Ni(ptdt)2- anion is located on an inversion center. Atoms Ni(1), C(1), C(2), S(1), S(2), S(3) and S(4) lie on a common plane A while the terminal propylenic group is bent. The mean deviation of the atoms from the least-squares plane is ca. 0.03 A° . Atoms S(7) and S(8) show the largest deviation from the plane at 2.062 and 1.998 A ° .The planarity of the molecule is better than the neutral ptdt(CH2CH2CN)2 molecule [Fig. 2(b)]. Atoms S(5), S(6), S(7), S(8), C(5) and C(6) form a plane B with the dihedral angle between planes A and B being 30.13 °. The square-planar Ni complex shows NiMS distances of 2.154(2) and 2.167(2) A ° Fig. 3(a) Crystal structure of (Ph4P)[Ni(ptdt)2]·1.4Me2CO. (b) Overlapping mode of Ni(ptdt)2- in (Ph4P)[Ni(ptdt)2]·1.4Me2CO.and SMNiMS angles of 92.93(7) and 87.07(7) °. The distances 304 J. Mater. Chem., 1998, 8(2), 301–307Table 4 Selected bond lengths (A° ) and angles (degrees) the Ni(ptdt)2- anion is deviated along the short axis of the for (Me4N)[Ni(ptdt)2]·Me2CO molecule. The interplanar distance is ca. 3.25 A ° on average. The shortest Ni,Ni distance is 14.87 A ° while the shortest Ni(1)MS(1) 2.163(1) S(11)MC(12) 1.763(4) intermolecular S,S contact is 3.320(3) A° [S(1),S(7)], corre- Ni(1)MS(2) 2.172(1) S(12)MC(11) 1.748(4) sponding to the transverse S,S short contact with the neigh- Ni(1)MS(9) 2.174(1) S(12)MC(12) 1.767(4) Ni(1)MS(10) 2.164(1) S(13)MC(13) 1.758(4) bouring chain.Along the c-axis, however, no interaction is S(1)MC(1) 1.712(4) S(13)MC(14) 1.756(4) expected because the large tetraphenylphosphonium cations S(2)MC(2) 1.717(4) S(14)MC(13) 1.745(4) prevent the overlap of anions in this direction.The acetone of S(3)MC(1) 1.763(4) S(14)MC(15) 1.748(4) crystallization shows slight evidence of disorder with one of S(3)MC(3) 1.761(4) S(15)MC(14) 1.753(4) the CMC bond lengths being a little shorter than the other S(4)MC(2) 1.767(4) S(15)MC(16) 1.815(5) [CMC=1.28(2), CNO 1.17(1), CMC 1.57(2) A ° ] and the S(4)MC(3) 1.755(4) S(16)MC(15) 1.747(4) S(5)MC(4) 1.760(4) S(16)MC(18) 1.808(5) angles deviate from 120 ° [134 (1), 112 (1), 104 (1)°]. The S(5)MC(5) 1.765(4) C(1)MC(2) 1.358(5) population of the acetone molecule was determined by least- S(6)MC(4) 1.753(4) C(3)MC(4) 1.352(5) squares refinement as 0.7.The stereoview of anion arrangement S(6)MC(6) 1.765(4) C(5)MC(6) 1.341(5) of (Ph4P)[Ni(ptdt)2]·1.4Me2CO is shown in Fig. 4. S(7)MC(5) 1.739(4) C(7)MC(8) 1.511(6) S(7)MC(7) 1.816(5) C(8)MC(9) 1.519(6) (Me4N)[Ni(ptdt)2]·Me2CO 2. The Ni(ptdt)2- anion is S(8)MC(6) 1.740(4) C(10)MC(11) 1.361(5) S(8)MC(9) 1.806(4) C(12)MC(13) 1.332(5) shown in Fig. 5 and selected bond lengths and angles are listed S(9)MC(10) 1.715(4) C(14)MC(15) 1.343(5) in Table 4.Atoms Ni(1), C(1), C(2), S(1), S(2), S(3), S(4), S(10)MC(11) 1.711(4) C(16)MC(17) 1.515(6) C(10), C(11), S(9), S(10), S(11) and S(12) are in a common S(11)MC(10) 1.759(4) C(17)MC(18) 1.519(7) plane and the terminal propylenic group is bent. The mean S(1)MNi(1)MS(2) 93.11(4) S(2)MNi(1)MS(9) 88.72(4) deviation of atoms from the least-squares plane is ca. 0.07 A ° . S(1)MNi(1)MS(9) 175.84(6) S(2)MNi(1)MS(10) 176.43(6) Atoms S(7), S(8) S(15) and S(16) show the largest deviation S(1)MNi(1)MS(10) 85.52(4) S(9)MNi(1)MS(10) 92.86(4) from the plane at 1.309, 1.390, 1.202 and 1.512 A ° , respectively. Thus the planarity of the molecule is fairly high. The almost square-planar Ni complex shows NiMS distance of 2.163(1), crystal structure of 2 is shown in Fig. 6(a). Fig. 6(b) shows that 2.172(1), 2.174(1) and 2.164(1) A° while the SMNiMS angles one of the ligands of Ni(ptdt)2- is overlapping with that of an within the five-membered ring are 93.11(4) and 92.86(4) ° the adjacent anion separated by about half of the unit of the remainder are 85.52(4) and 88.72(4) °, respectively.The molecule, forming a one-dimensional chain along [101]. The dihedral angle between the planes S(1)NiS(2) and S(3)NiS(4) overlapping mode of Ni(ptdt)2- is ring-over-bond type and is 4.86 °. The central CNC bond lengths, C(3)MC(4) and the interplanar distance is 3.30 A ° . The overlap in the anion C(12)MC(13) are 1.352(5) and 1.332(5) A ° , respectively. The chain of 2 is larger than that in 1.The shortest intermolecular S,S distance is 3.525(2) A ° [S(7),S(15)], shown in Fig. 6(a) as dotted lines. Along the [011] direction, the shortest transverse S,S and Ni,Ni distances are 3.559(2) A ° [S(8),S(13)] and 6.562(1) A° , respectively. The characteristic feature of stacking is short S,S contacts between the neighbouring chains along the [201] direction, which was not observed for 1 owing to the large tetraphenylphosphonium cation.The interaction is expected because the small tetramethylammonium cation does not prevent contacts of the anions in this direction. The acetone of crystallization is not disordered. Fig. 4 Stereoview of the crystal structure of (Ph4P)- [Ni(ptdt)2]·1.4Me2CO. Fig. 6 (a) Crystal structure of (Me4N)[Ni(ptdt)2]·Me2CO.(b) Fig. 5 ORTEP drawing of the monoanion Ni(ptdt)2- showing the atom labelling at the 50% probability level Overlapping mode of Ni(ptdt)2- in (Me4N)[Ni(ptdt)2]·Me2CO. J. Mater. Chem., 1998, 8(2), 301–307 305(Ph4P)2[Cu(ptdt)2]·1.2Me2CO 3. The Cu(ptdt)22- anion is shown in Fig. 7 and selected bond lengths and angles are listed in Table 5. The terminal propylenic group of Cu(ptdt)22- is bent as found for the Ni complex.A distorted tetrahedral geometry is observed around the Cu atom with CuMS distances of 2.279(4), 2.273(4), 2.282(4) and 2.265(4) A ° and SMCuMS angles of 93.6(1), 93.2(1), 140.3(2) and 142.0(2) °. The dihedral angle between the planes S(1)CuS(2) and S(9)CuS(10) is 54.2 °. The central CNC bond lengths C(3)MC(4) and C(12)MC(13) are 1.35(1) and 1.35(2) A ° , respectively.The geometry around the Cu atom is almost the same as in [epy]2[Cu(dmit)2] (epy=N-ethylpyridinium; dmit=4,5-dimercapto-1,3-dithiole- 2-thione).10 In this case the dihedral angle is 57.3 °. The crystal structure is shown in Fig. 8 and the schematic stacking pattern of 3 is shown in Fig. 9. The anions form a one-dimensional chain along the c-direction with both ligands, which overlap in ring-over-bond type with those of adjacent anions.The interplanar distance is ca. 3.39A ° and the Cu,Cu distance is 14.78 A ° . The shortest intermolecular S,S distance is 3.582(7) A ° [S(16),S(16)], which correspond to short transverse contacts between adjacent chains. The large tetraphenylphosphonium cations prevent overlapping along the b direction.The pconjugated systems of the ptdt ligand are large enough to form conduction pathways in the crystal. In the case of [epy]2[Cu(dmit)2], owing to the small size of the ligand, the stacking of Cu(dmit)2 is only via one side of the ligand, which prevents formation of a good conduction pathway. The next step for the development of new types of molecular conductors may be oxidation of the complexes.Magnetic susceptibilities The temperature dependence of the magnetic susceptibility of (Me4N)2[Cu(ptdt)2] within the temperature range 2–300 K Fig. 8 (a) Crystal structure of (Ph4P)2[Cu(ptdt)2]·1.2Me2CO. (b) Stereoview of (Ph4P)2[Cu(ptdt)2]·1.2Me2CO. Fig. 7 ORTEP drawing of the dianion Cu(ptdt)22- showing the atom labelling at the 50% probability level Table 5 Selected bond lengths (A° ) and angles (degrees) for (Ph4P)2[Cu(ptdt)2]·1.2Me2CO Cu(1)MS(1) 2.279(4) S(11)MC(12) 1.74(1) Cu(1)MS(2) 2.273(4) S(12)MC(11) 1.78(1) Cu(1)MS(9) 2.282(4) S(12)MC(12) 1.74(1) Cu(1)MS(10) 2.265(4) S(13)MC(13) 1.77(1) S(1)MC(1) 1.73(1) S(13)MC(14) 1.79(1) Fig. 9 Schematic molecular arrangement and overlapping mode of S(2)MC(2) 1.74(1) S(14)MC(13) 1.76(1) (Ph4P)2[Cu(ptdt)2]·1.2Me2CO S(3)MC(1) 1.77(1) S(14)MC(15) 1.74(1) S(3)MC(3) 1.76(1) S(15)MC(14) 1.75(1) S(4)MC(2) 1.75(1) S(15)MC(16) 1.81(1) S(4)MC(3) 1.75(1) S(16)MC(15) 1.72(1) obeys Curie behavior, indicating non-interacting spins for S(5)MC(4) 1.73(1) S(16)MC(18) 1.78(1) (Me4N)2[Cu(ptdt)2].The diamagnetic component of the mag- S(5)MC(5) 1.75(1) C(1)MC(2) 1.34(2) netic susceptibility was estimated by use of Pascal law to be S(6)MC(4) 1.76(1) C(3)MC(4) 1.35(1) S(6)MC(6) 1.76(1) C(5)MC(6) 1.35(2) -4.9×10-4 emu mol-1.11 The room temperature magnetic S(7)MC(5) 1.76(1) C(7)MC(8) 1.50(2) susceptibility of 9.8×10-4 emu mol-1 suggests 0.8 spins per S(7)MC(7) 1.81(2) C(8)MC(9) 1.48(2) molecule, which is consistent with the presence of Cu2+.S(8)MC(6) 1.72(1) C(10)MC(11) 1.34(2) S(8)MC(9) 1.84(1) C(12)MC(13) 1.35(2) Electrical resistivities S(9)MC(10) 1.74(1) C(14)MC(15) 1.35(2) S(10)MC(11) 1.72(1) C(17)MC(18) 1.53(2) The temperature dependence of the resistivity of S(11)MC(10) 1.76(1) C(16)MC(17) 1.51(2) (Me4N)[Ni (ptdt)2]·Me2CO was measured by usual four-probe S(1)MCu(1)MS(2) 93.6(1) S(2)MCu(1)MS(9) 142.0(2) method and was semiconducting (Fig. 10). The room tempera- S(1)MCu(1)MS(9) 101.6(1) S(2)MCu(1)MS(10) 96.9(1) ture conductivity is 1.4×10-3 S cm-1 and the activation S(1)MCu(1)MS(10) 140.3(2) S(9)MCu(1)MS(10) 93.2(1) energy is 9.9×10-2 eV. 306 J. Mater. Chem., 1998, 8(2), 301–307A. Sato for her help in magnetic susceptibility measurements. This work was partly supported by Grant-in Aid for Fundamental Research on ‘New Series of BETS Superconductors with Mixed Halide Gallium Anions’.References 1 Y. Misaki, H. Nishikawa, K. Kawakami, S. Koyanagi, T. Yamabe and M. Shiro, Chem. L ett., 1992, 2321. 2 N. L. Narvor, N. Robertson, T. Weyland, J. D. Kilburn, A. E. Underhill, M. Webster, N. Svenstrup and J. Becker, Chem. Commun., 1996, 1363; N. L. Narvor, N. Robertson, E. Wallace, J.D. Kilburn, A. E. Underhill, P. N. Bartlett and M. Webster, J. Chem. Soc., Dalton. T rans., 1996, 823. 3 M. Nakano, A. Kuroda, T. Maikawa and G. Matsubayashi, Mol. Cryst. L iq. Cryst., 1996, 284, 301. 4 C. Gemmell, G. C. Janairo, J. D. Kilburn, H. Ueck and A. E. Underhill, J. Chem. Soc., Perkin T rans., 1995, 2715. Fig. 10 Temperature dependence of the electrical resistivity of 5 Y.Misaki, H. Nishikawa, K. Kawakami, S. Koyanagi, T. Yamabe (Me4N)[Ni(ptdt)2]·Me2CO and M. Shiro, Chem. L ett., 1992, 2321. 6 International Tables for X-Ray Crystallography, Kynoch Press, Birmingham 1974, vol. IV. 7 TeXsan: Crystal Structure Analysis Package, Molecular Structure Corporation, version 1. 7–2a, 1995. Conclusion 8 C. K. Johnson, ORTEP II, Report ORNL-5138, Oak Ridge National Laboratory; Oak Ridge, TN, 1976. Two inevitable requirements for the design of the good conduc- 9 L.C. Porter, A. M. Kini and J. M. Williams, Acta Crystallogr., tors are: (1) the formation of conduction pathway and (2) the Sect. C, 1987, 43, 998. formation of charge carriers. As for requirement (1), the crystal 10 G. Matsubayashi, K. Takahashi and T. Takano, J. Chem.Soc., structures of 1, 2 and 3 show possibility of novel 2D or 3D Dalton T rans., 1988, 967. intermolecular contacts through ptdt ligands in place of ‘span- 11 L andolt-Bo�rnstein Zahlenwerte und Funktionen aus ning overlapping’ of the Ni(dmit)2 complexes, which is the only Naturwissenschaften und T echnik, Neue Serie II/11, Springer- Verlag, 1981. unique example of a 2D molecular arrangement of conducting 12 A. Kobayashi, T. Naito and H. Kobayashi, Phys. Rev. B., 1995, transition metal complexes.12–15 Moreover, a new molecular 51, 3198. conductor with p–d interactions will be expected if a magnetic 13 R. Kato, H. Kobayashi, H. Kim, Y. Sasaki, T. Mori and H. transition metal atom is incorporated.16 In order to meet Inokuchi, Chem. L ett., 1988, 865. requirement (2), further experiments are required. Very recently 14 A. Kobayashi and H. Kobayashi, Molecular Metals and black crystals of fairly conducting neutral Ni(ptdt)2 have been Superconductors Based on T ransition Metal Complexes, in Handbook of Organic ConductiveMolecules and Polymers, ed. H. S. obtained by electrocrystallization with a room temperature Nalwa, John Wiley & Sons, Ltd., 1997, vol 1, p. 276. conductivity of 2.1 S cm-1 and an activation energy of 0.11 eV. 15 A. Kobayashi, A. Sato, T. Naito and H. Kobayashi, Mol. Cryst. The conductivity is significantly higher than values normally L iq. Cryst., 1996, 284, 85. observed for other neutral complexes such as dithiolenes 16 H. Kobayashi, A. Miyamoto, R. Kato, F. Saka, A. Kobayashi, (<10-3 S cm-1) or TTF dithiolenes (<10-1 S cm-1).2 Y. Yamakita, Y. Furukawa, M. Tasumi and T. Watanabe, Phys. Rev. B: Condens.Matter, 1993, 47, 3500. We thank Mr. H. Fujiwara and Miss E. Arai of the Institute for Molecular Science for their valuable discussions and Miss Paper 7/04518B; Received 26th June, 1997 J. Mater. Chem., 1998, 8(2), 301–307 3